Systems and methods for etching metals and metal derivatives

ABSTRACT

Exemplary etching methods may include flowing a halogen-containing precursor into a substrate processing region of a semiconductor processing chamber. The methods may include contacting a substrate housed in the substrate processing region with the halogen-containing precursor. The substrate may define an exposed region of a transition-metal-containing material. The methods may also include removing the transition-metal-containing material. The flowing and the contacting may be plasma-free operations.

TECHNICAL FIELD

The present technology relates to semiconductor processes and equipment.More specifically, the present technology relates to selectively etchingtransition-metal-containing structures.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers, or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess that etches one material faster than another facilitating, forexample, a pattern transfer process. Such an etch process is said to beselective to the first material. As a result of the diversity ofmaterials, circuits, and processes, etch processes have been developedwith a selectivity towards a variety of materials.

Etch processes may be termed wet or dry based on the materials used inthe process. For example, a wet etch may preferentially remove someoxide dielectrics over other dielectrics and materials. However, wetprocesses may have difficulty penetrating some constrained trenches andalso may sometimes deform the remaining material. Dry etches produced inlocal plasmas formed within the substrate processing region canpenetrate more constrained trenches and exhibit less deformation ofdelicate remaining structures. However, local plasmas may damage thesubstrate through the production of electric arcs as they discharge.

Thus, there is a need for improved systems and methods that can be usedto produce high quality devices and structures. These and other needsare addressed by the present technology.

SUMMARY

Exemplary etching methods may include flowing a halogen-containingprecursor into a substrate processing region of a semiconductorprocessing chamber. The methods may include contacting a substratehoused in the substrate processing region with the halogen-containingprecursor. The substrate may define an exposed region of atransition-metal-containing material. The methods may also includeremoving the transition-metal-containing material. The flowing and thecontacting may be plasma-free operations.

In some embodiments, the halogen-containing precursor may be or includeone or more materials selected from the group including nitrogentrifluoride, diatomic fluorine, a precursor comprising carbon andfluorine, or chlorine trifluoride. The etching method may be performedat a temperature greater than or about 200° C. The etching method may beperformed at a pressure greater than or about 0.1 Torr. The etchingmethod may be performed at a pressure less than or about 50 Torr. Insome embodiments the methods may include a pre-treatment may beperformed prior to flowing the halogen-containing precursor. Thepre-treatment may be or include contacting the substrate with a plasmaincluding one or more of oxygen, hydrogen, or nitrogen. In someembodiments the methods may include a post-treatment performedsubsequent the etching method. The post-treatment may include contactingthe substrate with a plasma including one or more of oxygen, hydrogen,or nitrogen. The transition-metal-containing material may be or includeone or more of tungsten, molybdenum, titanium, or chromium. Thetransition-metal-containing material may be selected from the groupincluding tungsten, titanium nitride, molybdenum, tungsten silicide,molybdenum silicide, tungsten silicon nitride, tungsten silicon oxide,molybdenum silicon nitride, molybdenum silicon oxide, chromium, chromiumsilicide, tungsten chromium, or molybdenum chromium.

Some embodiments of the present technology may also encompass etchingmethods. The methods may include flowing an oxygen-containing precursorinto a substrate processing region of a semiconductor processingchamber. The methods may include contacting a substrate housed in thesubstrate processing region with the oxygen-containing precursor. Thesubstrate may define an exposed region of a transition-metal-containingmaterial. The methods may include oxidizing the exposed region of thetransition-metal-containing material to produce an oxidized material.The methods may include flowing a halogen-containing precursor into thesubstrate processing region of the semiconductor processing chamber. Thehalogen-containing precursor may be characterized by a gas densitygreater than or about 5 g/L. The methods may include contacting thesubstrate with the halogen-containing precursor. The methods may alsoinclude removing the oxidized material.

In some embodiments, the halogen-containing precursor may include atransition metal. The halogen-containing precursor may include tungsten.The transition-metal-containing material may be or include titaniumsilicon nitride, tantalum silicon nitride, hafnium silicon oxide,hafnium silicon nitride, or molybdenum. The halogen-containing precursormay be maintained plasma free during the etching method. The etchingmethod may be performed at a temperature greater than or about 200° C.The etching method may be performed at a pressure greater than or about0.1 Torr. The etching method may be performed at a pressure less than orabout 50 Torr. The methods may also include a pre-treatment performedprior to flowing the halogen-containing precursor. The pre-treatment mayinclude contacting the substrate with a plasma including one or more ofoxygen, hydrogen, or nitrogen. The method may also include apost-treatment performed subsequent the etching method. Thepost-treatment may include contacting the substrate with a plasmaincluding one or more of oxygen, hydrogen, or nitrogen. Theoxygen-containing precursor may be plasma enhanced prior to contactingthe substrate.

Such technology may provide numerous benefits over conventional systemsand techniques. For example, the processes may allow dry etching to beperformed that may protect features of the substrate. Additionally, theprocesses may selectively remove transition-metal-containing filmsrelative to other exposed materials on the substrate. These and otherembodiments, along with many of their advantages and features, aredescribed in more detail in conjunction with the below description andattached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedtechnology may be realized by reference to the remaining portions of thespecification and the drawings.

FIG. 1 shows a top plan view of one embodiment of an exemplaryprocessing system according to some embodiments of the presenttechnology.

FIG. 2A shows a schematic cross-sectional view of an exemplaryprocessing chamber according to some embodiments of the presenttechnology.

FIG. 2B shows a detailed view of a portion of the processing chamberillustrated in FIG. 2A according to some embodiments of the presenttechnology.

FIG. 3 shows a bottom plan view of an exemplary showerhead according tosome embodiments of the present technology.

FIG. 4 shows exemplary operations in a method according to someembodiments of the present technology.

FIG. 5 shows exemplary operations in a method according to someembodiments of the present technology.

Several of the figures are included as schematics. It is to beunderstood that the figures are for illustrative purposes, and are notto be considered of scale unless specifically stated to be of scale.Additionally, as schematics, the figures are provided to aidcomprehension and may not include all aspects or information compared torealistic representations, and may include additional or exaggeratedmaterial for illustrative purposes.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a letter thatdistinguishes among the similar components. If only the first referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same first reference labelirrespective of the letter.

DETAILED DESCRIPTION

Diluted acids may be used in many different semiconductor processes forcleaning substrates and removing materials from those substrates. Forexample, diluted hydrofluoric acid can be an effective etchant for manymetal-containing materials, and may be used to remove these materialsfrom substrate surfaces. After the etching or cleaning operation iscomplete, the acid may be dried from the wafer or substrate surface.Using dilute hydrofluoric acid (“DHF”) may be termed a “wet” etch, andthe diluent is often water. Additional etching processes may be usedthat utilize precursors delivered to the substrate. For example, plasmaenhanced processes may also selectively etch materials by enhancingprecursors through the plasma to perform a dry etch.

Although wet etchants using aqueous solutions or water-based processesmay operate effectively for certain substrate structures, the water maypose challenges in a variety of conditions. For example, utilizing waterduring etch processes may cause issues when disposed on substratesincluding metal materials. For example, certain later fabricationprocesses, such as recessing gaps, removing oxide dielectric, or otherprocesses to remove oxygen-containing materials, may be performed afteran amount of metallization has been formed on a substrate. If water isutilized in some fashion during the etching, an electrolyte may beproduced, which when contacting the metal material, may cause galvaniccorrosion to occur between dissimilar metals, and the metal may becorroded or displaced in various processes. In addition, because of thesurface tension of the water diluent, pattern deformation and collapsemay occur with minute structures. The water-based material may also beincapable of penetrating some high aspect ratio features due to surfacetension effects.

Plasma etching may overcome the issues associated with water-basedetching, although additional issues may occur. Many metal materials,such as transition metal materials, may be formed as oxides or nitrides,which operate as dielectrics in many semiconductor structures, andexhibit dielectric properties. Because of the dielectric nature, thesetransition metal materials do not readily conduct electricity.Accordingly, when charged plasma species are flowed towards thesematerials, charge buildup may occur along the surface of thetransition-metal-based dielectric. Once accumulation has surpassed athreshold, the electrical voltage may cause breakdown, which can damagethe transition metal material.

The present technology overcomes these issues by performing one or moredry etch process that may be plasma free during the etching. Byutilizing particular precursors that may facilitate halogen dissociationto provide etchant materials, an etch process may be performed that mayprotect the surrounding structures. Additionally, the materials andconditions used may allow improved etching relative to conventionaltechniques.

Although the remaining disclosure will routinely identify specificetching processes utilizing the disclosed technology, it will be readilyunderstood that the systems and methods are equally applicable todeposition and cleaning processes as may occur in the describedchambers, as well as other etching technology including mid andback-end-of-line processing and other etching that may be performed witha variety of exposed materials that may be maintained or substantiallymaintained. Accordingly, the technology should not be considered to beso limited as for use with the exemplary etching processes or chambersalone. Moreover, although an exemplary chamber is described to providefoundation for the present technology, it is to be understood that thepresent technology can be applied to virtually any semiconductorprocessing chamber that may allow the operations described.

FIG. 1 shows a top plan view of one embodiment of a processing system100 of deposition, etching, baking, and curing chambers according toembodiments. In the figure, a pair of front opening unified pods (FOUPs)102 supply substrates of a variety of sizes that are received by roboticarms 104 and placed into a low pressure holding area 106 before beingplaced into one of the substrate processing chambers 108 a-f, positionedin tandem sections 109 a-c. A second robotic arm 110 may be used totransport the substrate wafers from the holding area 106 to thesubstrate processing chambers 108 a-f and back. Each substrateprocessing chamber 108 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, orientation, and othersubstrate processes.

The substrate processing chambers 108 a-f may include one or more systemcomponents for depositing, annealing, curing and/or etching a dielectricfilm on the substrate wafer. In one configuration, two pairs of theprocessing chambers, e.g., 108 c-d and 108 e-f, may be used to depositdielectric material on the substrate, and the third pair of processingchambers, e.g., 108 a-b, may be used to etch the deposited dielectric.In another configuration, all three pairs of chambers, e.g., 108 a-f,may be configured to etch a dielectric film on the substrate. Any one ormore of the processes described may be carried out in chamber(s)separated from the fabrication system shown in different embodiments. Itwill be appreciated that additional configurations of deposition,etching, annealing, and curing chambers for dielectric films arecontemplated by system 100.

FIG. 2A shows a cross-sectional view of an exemplary process chambersystem 200 with partitioned plasma generation regions within theprocessing chamber. During film etching, e.g., titanium nitride,tantalum nitride, tungsten, silicon, polysilicon, silicon oxide, siliconnitride, silicon oxynitride, silicon oxycarbide, etc., a process gas maybe flowed into the first plasma region 215 through a gas inlet assembly205. A remote plasma system (RPS) 201 may optionally be included in thesystem, and may process a first gas which then travels through gas inletassembly 205. The inlet assembly 205 may include two or more distinctgas supply channels where the second channel (not shown) may bypass theRPS 201, if included.

A cooling plate 203, faceplate 217, ion suppressor 223, showerhead 225,and a substrate support 265, having a substrate 255 disposed thereon,are shown and may each be included according to embodiments. Thepedestal 265 may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate, whichmay be operated to heat and/or cool the substrate or wafer duringprocessing operations. The wafer support platter of the pedestal 265,which may include aluminum, ceramic, or a combination thereof, may alsobe resistively heated in order to achieve relatively high temperatures,such as from up to or about 100° C. to above or about 1100° C., using anembedded resistive heater element.

The faceplate 217 may be pyramidal, conical, or of another similarstructure with a narrow top portion expanding to a wide bottom portion.The faceplate 217 may additionally be flat as shown and include aplurality of through-channels used to distribute process gases. Plasmagenerating gases and/or plasma excited species, depending on use of theRPS 201, may pass through a plurality of holes, shown in FIG. 2B, infaceplate 217 for a more uniform delivery into the first plasma region215.

Exemplary configurations may include having the gas inlet assembly 205open into a gas supply region 258 partitioned from the first plasmaregion 215 by faceplate 217 so that the gases/species flow through theholes in the faceplate 217 into the first plasma region 215. Structuraland operational features may be selected to prevent significant backflowof plasma from the first plasma region 215 back into the supply region258, gas inlet assembly 205, and fluid supply system 210. The faceplate217, or a conductive top portion of the chamber, and showerhead 225 areshown with an insulating ring 220 located between the features, whichallows an AC potential to be applied to the faceplate 217 relative toshowerhead 225 and/or ion suppressor 223. The insulating ring 220 may bepositioned between the faceplate 217 and the showerhead 225 and/or ionsuppressor 223 enabling a capacitively coupled plasma (CCP) to be formedin the first plasma region. A baffle (not shown) may additionally belocated in the first plasma region 215, or otherwise coupled with gasinlet assembly 205, to affect the flow of fluid into the region throughgas inlet assembly 205.

The ion suppressor 223 may comprise a plate or other geometry thatdefines a plurality of apertures throughout the structure that areconfigured to suppress the migration of ionically-charged species out ofthe first plasma region 215 while allowing uncharged neutral or radicalspecies to pass through the ion suppressor 223 into an activated gasdelivery region between the suppressor and the showerhead. Inembodiments, the ion suppressor 223 may comprise a perforated plate witha variety of aperture configurations. These uncharged species mayinclude highly reactive species that are transported with less reactivecarrier gas through the apertures.

As noted above, the migration of ionic species through the holes may bereduced, and in some instances completely suppressed. Controlling theamount of ionic species passing through the ion suppressor 223 mayadvantageously provide increased control over the gas mixture broughtinto contact with the underlying wafer substrate, which in turn mayincrease control of the deposition and/or etch characteristics of thegas mixture. For example, adjustments in the ion concentration of thegas mixture can significantly alter its etch selectivity, e.g.,SiNx:SiOx etch ratios, Si:SiOx etch ratios, etc. In alternativeembodiments in which deposition is performed, it can also shift thebalance of conformal-to-flowable style depositions for dielectricmaterials.

The plurality of apertures in the ion suppressor 223 may be configuredto control the passage of the activated gas, i.e., the ionic, radical,and/or neutral species, through the ion suppressor 223. For example, theaspect ratio of the holes, or the hole diameter to length, and/or thegeometry of the holes may be controlled so that the flow ofionically-charged species in the activated gas passing through the ionsuppressor 223 is reduced. The holes in the ion suppressor 223 mayinclude a tapered portion that faces the plasma excitation region 215,and a cylindrical portion that faces the showerhead 225. The cylindricalportion may be shaped and dimensioned to control the flow of ionicspecies passing to the showerhead 225. An adjustable electrical bias mayalso be applied to the ion suppressor 223 as an additional means tocontrol the flow of ionic species through the suppressor.

The ion suppressor 223 may function to reduce or eliminate the amount ofionically charged species traveling from the plasma generation region tothe substrate. Uncharged neutral and radical species may still passthrough the openings in the ion suppressor to react with the substrate.It should be noted that the complete elimination of ionically chargedspecies in the reaction region surrounding the substrate may not beperformed in embodiments. In certain instances, ionic species areintended to reach the substrate in order to perform the etch and/ordeposition process. In these instances, the ion suppressor may help tocontrol the concentration of ionic species in the reaction region at alevel that assists the process.

Showerhead 225 in combination with ion suppressor 223 may allow a plasmapresent in first plasma region 215 to avoid directly exciting gases insubstrate processing region 233, while still allowing excited species totravel from chamber plasma region 215 into substrate processing region233. In this way, the chamber may be configured to prevent the plasmafrom contacting a substrate 255 being etched. This may advantageouslyprotect a variety of intricate structures and films patterned on thesubstrate, which may be damaged, dislocated, or otherwise warped ifdirectly contacted by a generated plasma. Additionally, when plasma isallowed to contact the substrate or approach the substrate level, therate at which oxide species etch may increase. Accordingly, if anexposed region of material is oxide, this material may be furtherprotected by maintaining the plasma remotely from the substrate.

The processing system may further include a power supply 240electrically coupled with the processing chamber to provide electricpower to the faceplate 217, ion suppressor 223, showerhead 225, and/orpedestal 265 to generate a plasma in the first plasma region 215 orprocessing region 233. The power supply may be configured to deliver anadjustable amount of power to the chamber depending on the processperformed. Such a configuration may allow for a tunable plasma to beused in the processes being performed. Unlike a remote plasma unit,which is often presented with on or off functionality, a tunable plasmamay be configured to deliver a specific amount of power to the plasmaregion 215. This in turn may allow development of particular plasmacharacteristics such that precursors may be dissociated in specific waysto enhance the etching profiles produced by these precursors.

A plasma may be ignited either in chamber plasma region 215 aboveshowerhead 225 or substrate processing region 233 below showerhead 225.Plasma may be present in chamber plasma region 215 to produce theradical precursors from an inflow of, for example, a fluorine-containingprecursor or other precursor. An AC voltage typically in the radiofrequency (RF) range may be applied between the conductive top portionof the processing chamber, such as faceplate 217, and showerhead 225and/or ion suppressor 223 to ignite a plasma in chamber plasma region215 during deposition. An RF power supply may generate a high RFfrequency of 13.56 MHz but may also generate other frequencies alone orin combination with the 13.56 MHz frequency.

FIG. 2B shows a detailed view 253 of the features affecting theprocessing gas distribution through faceplate 217. As shown in FIGS. 2Aand 2B, faceplate 217, cooling plate 203, and gas inlet assembly 205intersect to define a gas supply region 258 into which process gases maybe delivered from gas inlet 205. The gases may fill the gas supplyregion 258 and flow to first plasma region 215 through apertures 259 infaceplate 217. The apertures 259 may be configured to direct flow in asubstantially unidirectional manner such that process gases may flowinto processing region 233, but may be partially or fully prevented frombackflow into the gas supply region 258 after traversing the faceplate217.

The gas distribution assemblies such as showerhead 225 for use in theprocessing chamber section 200 may be referred to as dual channelshowerheads (DCSH) and are additionally detailed in the embodimentsdescribed in FIG. 3. The dual channel showerhead may provide for etchingprocesses that allow for separation of etchants outside of theprocessing region 233 to provide limited interaction with chambercomponents and each other prior to being delivered into the processingregion.

The showerhead 225 may comprise an upper plate 214 and a lower plate216. The plates may be coupled with one another to define a volume 218between the plates. The coupling of the plates may be so as to providefirst fluid channels 219 through the upper and lower plates, and secondfluid channels 221 through the lower plate 216. The formed channels maybe configured to provide fluid access from the volume 218 through thelower plate 216 via second fluid channels 221 alone, and the first fluidchannels 219 may be fluidly isolated from the volume 218 between theplates and the second fluid channels 221. The volume 218 may be fluidlyaccessible through a side of the gas distribution assembly 225.

FIG. 3 is a bottom view of a showerhead 325 for use with a processingchamber according to embodiments. Showerhead 325 may correspond with theshowerhead 225 shown in FIG. 2A. Through-holes 365, which show a view offirst fluid channels 219, may have a plurality of shapes andconfigurations in order to control and affect the flow of precursorsthrough the showerhead 225. Small holes 375, which show a view of secondfluid channels 221, may be distributed substantially evenly over thesurface of the showerhead, even amongst the through-holes 365, and mayhelp to provide more even mixing of the precursors as they exit theshowerhead than other configurations.

The chamber discussed previously may be used in performing exemplarymethods including etching methods. As etch processes continue to evolve,different precursors may operate more effectively with certainmetal-containing materials over others. For example, depending oncrystalline structure characteristics of materials to be etched, as wellas chemical precursors to be used in etchants, combinations can bedeveloped to further etch additional materials. For example, Group 6transition metals, which may include chromium, molybdenum, and tungsten,are being used more readily in semiconductor processing, and techniquesfor selectively removing these metals or derivatives of these metals areneeded. As metals, and as derivatives, the materials may produce avariety of different structures that may be amenable to certainetchants. For example, the individual metals and certain derivatives maybe etched using halogen-containing precursors. To protect dielectricstructures from plasma, and to protect small features from water aspreviously described, thermal etching may be used to remove thesematerials. However, because of the different characteristics of thesematerials, different derivatives may not be amenable to the same etchantprecursors for thermal etching.

Accordingly, the present technology provides multiple etchantcombinations for thermal etching of these metals, which advantageouslymay also apply to certain other transition-metal-containing materials,including some titanium, tantalum, and hafnium-containing materials. Themethods will be discussed in order with the first method based on afirst set of halogen-containing materials, and the second method basedon a second halogen-containing precursor. Because these precursors mayhave different characteristics, they may etch differently. While bothetch processes include a thermal etch of transition-metal-containingmaterials, the two etches may operate more effectively with differentsets of materials as will be described in detail below.

FIG. 4 shows exemplary operations in a method 400 according toembodiments of the present technology. Method 400 may include one ormore operations prior to the initiation of the method, including frontend processing, deposition, gate formation, etching, polishing,cleaning, or any other operations that may be performed prior to thedescribed operations. The method may include a number of optionaloperations, which may or may not be specifically associated with someembodiments of methods according to the present technology. For example,many of the operations are described in order to provide a broader scopeof the processes performed, but are not critical to the technology, ormay be performed by alternative methodology as will be discussed furtherbelow.

Method 400 may or may not involve optional operations to develop thesemiconductor structure to a particular fabrication operation. It is tobe understood that method 400 may be performed on any number ofsemiconductor structures, including exemplary structures on which atransition metal material removal operation may be performed. Exemplarysemiconductor structures may include a trench, via, or other recessedfeatures that may include one or more exposed materials. For example, anexemplary substrate may contain silicon or some other semiconductorsubstrate material as well as interlayer dielectric materials throughwhich a recess, trench, via, or isolation structure may be formed.Exposed materials may be or include metal materials such as for a gate,a dielectric material, a contact material, a transistor material, or anyother material that may be used in semiconductor processes. In someembodiments exemplary substrates may include atransition-metal-containing material, such as tungsten, molybdenum,titanium, chromium, or some combination or derivative of thesematerials. The transition-metal-containing material may be exposedrelative to one or more other materials including metals, otherdielectrics including silicon oxide or nitride, or any of a number ofother semiconductor materials relative to which thetransition-metal-containing material is to be removed.

It is to be understood that the noted structure is not intended to belimiting, and any of a variety of other semiconductor structuresincluding transition-metal-containing materials are similarlyencompassed. Other exemplary structures may include two-dimensional andthree-dimensional structures common in semiconductor manufacturing, andwithin which a transition-metal-containing material is to be removedrelative to one or more other materials, as some embodiments of thepresent technology may selectively remove certain transition metals andsome transition-metal-containing materials relative to other exposedmaterials, such as silicon-containing materials, and any of the othermaterials discussed elsewhere. Additionally, although ahigh-aspect-ratio structure may benefit from the present technology, thetechnology may be equally applicable to lower aspect ratios and anyother structures.

For example, layers of material according to the present technology maybe characterized by any aspect ratios or the height-to-width ratio ofthe structure, although in some embodiments the materials may becharacterized by larger aspect ratios, which may not allow sufficientetching utilizing conventional technology or methodology. For example,in some embodiments the aspect ratio of any layer of an exemplarystructure may be greater than or about 10:1, greater than or about 20:1,greater than or about 30:1, greater than or about 40:1, greater than orabout 50:1, or greater. Additionally, each layer may be characterized bya reduced width or thickness less than or about 100 nm, less than orabout 80 nm, less than or about 60 nm, less than or about 50 nm, lessthan or about 40 nm, less than or about 30 nm, less than or about 20 nm,less than or about 10 nm, less than or about 5 nm, less than or about 1nm, or less, including any fraction of any of the stated numbers, suchas 20.5 nm, 1.5 nm, etc. This combination of high aspect ratios andminimal thicknesses may frustrate many conventional etching operations,or require substantially longer etch times to remove a layer, along avertical or horizontal distance through a confined width. Moreover,damage to or removal of other exposed layers may occur with conventionaltechnologies as well.

Method 400 may be performed to remove an exposedtransition-metal-containing material in embodiments, although any numberof materials that may be characterized by similar structural or materialcharacteristics may be removed in any number of structures inembodiments of the present technology. The methods may include specificoperations for the removal of transition-metal-containing materials, andmay include one or more optional operations to prepare or treat thetransition-metal-containing materials. For example, an exemplarysubstrate structure may have previous processing residues on a film tobe removed, such as a tungsten, molybdenum, chromium, ortitanium-containing material. For example, residual photoresist orbyproducts from previous processing may reside on the material layer.These materials may prevent access to the transition-metal-containingmaterial, or may interact with etchants differently than a cleantransition-metal-containing surface, which may frustrate one or moreaspects of the etching. Accordingly, in some embodiments an optionalpre-treatment of the transition-metal-containing film or material mayoccur at optional operation 405. Exemplary pre-treatment operations mayinclude a thermal treatment, wet treatment, or plasma treatment, forexample, which may be performed in chamber 200 as well as any number ofchambers that may be included on system 100 described above.

In one exemplary plasma treatment, a remote or local plasma may bedeveloped from a precursor intended to interact with residues in one ormore ways. For example, utilizing chambers such as chamber 200 describedabove, either a remote or local plasma may be produced from one or moreprecursors. For example, an oxygen-containing precursor, ahydrogen-containing precursor, a nitrogen-containing precursor, ahelium-containing precursor, or some other precursor may be flowed intoa remote plasma region or into the processing region, where a plasma maybe struck. The plasma effluents may be flowed to the substrate, and maycontact the residue material. The plasma process may be either physicalor chemical depending on the material to be removed to expose thetransition-metal-containing material. For example, plasma effluents maybe flowed to contact and physically remove the residue, such as by asputtering operation, or the precursors may be flowed to interact withthe residues to produce volatile byproducts that may be removed from thechamber.

Exemplary precursors used in the pre-treatment may be or includehydrogen, a hydrocarbon, water vapor, an alcohol, hydrogen peroxide, orother materials that may include hydrogen as would be understood by theskilled artisan. Exemplary oxygen-containing precursors may includemolecular oxygen, ozone, nitrous oxide, nitric oxide, or otheroxygen-containing materials. Nitrogen gas may also be used, or acombination precursor having one or more of hydrogen, oxygen, and/ornitrogen may be utilized to remove particular residues. Once the residueor byproducts have been removed, a clean transition-metal-containingmaterial surface may be exposed for etching.

Method 400 may include flowing a halogen-containing precursor into thesubstrate processing region of a semiconductor processing chamberhousing the described substrate, or some other substrate, at operation410. The halogen-containing precursor may be flowed through a remoteplasma region of the processing chamber, such as region 215 describedabove, although in some embodiments method 400 may not utilize plasmaeffluents during the etching operations. For example, method 400 mayflow a fluorine-containing or other halogen-containing precursor to thesubstrate without exposing the precursor to a plasma, and may performthe removal of the transition-metal-containing material withoutproduction of plasma effluents. At operation 415, the halogen-containingprecursor may contact a semiconductor substrate including an exposedtransition-metal-containing material. The precursor may interact withthe exposed transition-metal-containing material and may etch or removethe material at operation 420.

As noted above, the present technology may be performed without plasmadevelopment during the etching operations 410-420. By utilizingparticular precursors, and performing the etching within certain processconditions, a plasma-free removal may be performed, and the removal mayalso be a dry etch for certain transition-metal-containing materials.Accordingly, techniques according to aspects of the present technologymay be performed to remove certain transition-metal-containing materialsfrom narrow features, as well as high aspect ratio features, and thindimensions that may otherwise be unsuitable for wet etching. An optionaloperation may be performed to clear the substrate or chamber of residuesand may include a post-treatment at optional operation 425. Thepost-treatment may include similar operations as the pre-treatment, andmay include any of the precursors or operations discussed above for thepre-treatment. The post-treatment may clear residual transition metal orbyproducts from the substrate or chamber in some embodiments. It is tobe understood that although the pre-treatment and/or post-treatmentoperations may include plasma generation and plasma effluent delivery tothe substrate, plasma may not be formed during the etching operations.For example, in some embodiments no plasma may be generated while thehalogen-containing precursor or precursors are being delivered into theprocessing chamber. Additionally, in some embodiments, the etchingprecursors may be hydrogen-free in some embodiments, and the etchingmethod may not include hydrogen-containing precursors during theetching, although hydrogen-containing precursors may be used duringeither or both of the optional pre-treatment or post-treatmentoperations.

The structures etched according to embodiments of the present technologymay include transition-metal-containing materials as noted above, andmay specifically include one or more of tungsten, molybdenum, orchromium, and may also include certain other transition metal materials,such as some titanium-containing materials, for example. One differencebetween method 400 and method 500 discussed below may include adifferent set of etchant materials. For example, method 400 may notinclude a transition metal in the etchants, while method 500 may bebased on a transition metal etchant. Accordingly, the two etchants maybe suited to different structures for etching. For example, transitionmetal etchants may be less capable or incapable of etching certaintransition metals and derivatives. For example, a tungsten halideprecursor may be challenged in removing tungsten and tungsten-containingmaterials, as well as molybdenum and chromium. Similarly, certainderivatives of these metals, including certain silicides may not besuitably etched, or etched with sufficient selectivity withtungsten-containing materials. However, certain halogen-containingprecursors that may not include a transition metal may more readilyremove some of these materials.

The precursors used in method 400 may include halogen-containingprecursors, and may include one or more of fluorine or chlorine in someembodiments. The specific precursors may be based on bonding orstability of the precursors as well as the structures to be etched. Forexample, for certain structures identified below, the halogen-containingprecursor may be selected from the group consisting of nitrogentrifluoride, diatomic fluorine, a carbon-and-fluorine-containingprecursor, and chlorine trifluoride. Exemplarycarbon-and-fluorine-containing precursors may be characterized by one ormore carbon-fluoride bonds. Some exemplary precursors may include CH₃F,CH₂F₂, CHF₃, CF₄, as well as other carbon-and-fluorine-containingprecursors, which may include one or more of oxygen, nitrogen, hydrogen,or other materials.

The structures to be etched may include particular combinations ofmaterial, as well as certain transition metals. For example,transition-metal-containing materials that may be suitably etched withthese precursors in method 400 may include tungsten, molybdenum, andchromium, as well as certain derivatives and combinations of thesematerials. For example, additional materials that may be etched withthese precursors may include alloys such as tungsten chromium andmolybdenum chromium. Additional materials that may be etched may includetungsten silicide, molybdenum silicide, tungsten silicon nitride,tungsten silicon oxide, molybdenum silicon nitride, molybdenum siliconoxide, chromium silicide, as well as titanium nitride. During etching,these specific materials may each form low vapor pressure metalfluorides with the noted etchant precursors, which at temperaturesdiscussed below, may be readily removed from a processing chamber assublimated byproducts. Accordingly, the methods may also be employed onmaterials that have similar crystalline or bonding structures with anyof the noted materials, as well as similar physical or chemicalcharacteristics. Because certain embodiments may not include ahydrogen-containing material, the materials may selectively etch thenoted transition-metal-containing materials relative to silicon oxide,for example, with almost perfect selectivity, as the silicon oxide maynot etch with certain precursors alone, such as nitrogen trifluoride,for example.

Processing conditions may impact and facilitate etching according to thepresent technology. Because the etch reaction may proceed based onthermal dissociation of halogen from the noted etchant precursors, thetemperatures may be at least partially dependent on the particularhalogen of the precursor in order to initiate dissociation. For example,as temperature increases above or about 200° C., etching may begin tooccur or increase, which may indicate dissociation of the precursor,and/or activation of the reaction with the exposed transition metalmaterial. As temperature continues to increase, dissociation may befurther facilitated as may the reaction with thetransition-metal-containing material. Additionally, subsequent theremoval, precursor delivery may be halted, while the substrate ismaintained at any noted temperature, which may facilitate removal ofresidual halogen, which may have embedded within other exposed materialsduring the etching operations. Accordingly, in some embodimentssubsequent removal, the precursor delivery may be halted, and thesubstrate may be maintained above 100° C. for a period of time greaterthan or about 1 second, greater than or about 5 seconds, greater than orabout 10 seconds, greater than or about 20 seconds, greater than orabout 30 seconds, or more.

In some embodiments of the present technology, etching methods may beperformed at substrate, pedestal, and/or chamber temperatures above orabout 200° C., and may be performed at temperatures above or about 250°C., above or about 300° C., above or about 350° C., above or about 400°C., above or about 450° C., above or about 500° C., or higher. Thetemperature may also be maintained at any temperature within theseranges, within smaller ranges encompassed by these ranges, or betweenany of these ranges. In some embodiments the method may be performed onsubstrates that may have a number of produced features, which mayproduce a thermal budget. Accordingly, in some embodiments, the methodsmay be performed at temperatures below or about 800° C., and may beperformed at temperatures below or about 750° C., below or about 700°C., below or about 650° C., below or about 600° C., below or about 550°C., below or about 500° C., or lower.

The pressure within the chamber may also affect the operations performedas well as affect at what temperature the halogen may dissociate.Accordingly, in some embodiments the pressure may be maintained belowabout 50 Torr, below or about 40 Torr, below or about 30 Torr, below orabout 25 Torr, below or about 20 Torr, below or about 15 Torr, below orabout 10 Torr, below or about 9 Torr, below or about 8 Torr, below orabout 7 Torr, below or about 6 Torr, below or about 5 Torr, below orabout 4 Torr, below or about 3 Torr, below or about 2 Torr, below orabout 1 Torr, below or about 0.1 Torr, or less. The pressure may also bemaintained at any pressure within these ranges, within smaller rangesencompassed by these ranges, or between any of these ranges. Forexample, etch amount may be facilitated and may initiate as pressureincreases above about 1 Torr. Additionally, as pressure continues toincrease, etching may improve up to a point before beginning to reduce,and eventually cease as pressure continues to increase.

Without being bound to any particular theory, pressure within thechamber may affect processing with precursors described above. At lowpressures, flow across a substrate may be reduced, and dissociation maysimilarly be reduced. As pressure increases, interactions between theetchant precursor and the substrate may increase, which may increasereactions and etch rates. However, as pressure continues to increase,recombination of the dissociated halogen atoms may increase due to therelative stability of the molecules. Thus, the precursors mayeffectively be pumped back out of the chamber without reacting with thesubstrate. Additionally, interactions with the transition metal materialsurface may be suppressed as pressure continues to increase, orbyproduct material may be reintroduced to the film being etched, furtherlimiting removal. Accordingly, in some embodiments, pressure within theprocessing chamber may be maintained below or about 10 Torr in someembodiments.

Flow rates of the halogen-containing precursor may be tuned, includingin situ, to control the etch process. For example, a flow rate of thehalogen-containing precursor may be reduced, maintained, or increasedduring the removal operations. By increasing the flow rate of thehalogen-containing precursor, etch rates may be increased up to a pointof saturation. During any of the operations of method 400, the flow rateof the fluorine-containing precursor may be between about 5 sccm andabout 1,000 sccm. Additionally, the flow rate of the halogen-containingprecursor may be maintained below or about 900 sccm, below or about 800sccm, below or about 700 sccm, below or about 600 sccm, below or about500 sccm, below or about 400 sccm, below or about 300 sccm, below orabout 200 sccm, below or about 100 sccm, or less. The flow rate may alsobe between any of these stated flow rates, or within smaller rangesencompassed by any of these numbers.

Adding further control to the etch process, the halogen-containingprecursor may be pulsed in some embodiments, and may be deliveredthroughout the etch process either continually or in a series of pulses,which may be consistent or varying over time. The pulsed delivery may becharacterized by a first period of time during which thehalogen-containing precursor is flowed, and a second period of timeduring which the halogen-containing precursor is paused or halted. Thetime periods for any pulsing operation may be similar or different fromone another with either time period being longer. In embodiments eitherperiod of time or a continuous flow of precursor may be performed for atime period greater than or about 1 second, and may be greater than orabout 2 seconds, greater than or about 3 seconds, greater than or about4 seconds, greater than or about 5 seconds, greater than or about 6seconds, greater than or about 7 seconds, greater than or about 8seconds, greater than or about 9 seconds, greater than or about 10seconds, greater than or about 11 seconds, greater than or about 12seconds, greater than or about 13 seconds, greater than or about 14seconds, greater than or about 15 seconds, greater than or about 20seconds, greater than or about 30 seconds, greater than or about 45seconds, greater than or about 60 seconds, or longer. The times may alsobe any smaller range encompassed by any of these ranges. In someembodiments as delivery of the precursor occurs for longer periods oftime, etch rate may increase.

By performing operations according to embodiments of the presenttechnology, the noted transition-metal-containing materials may beetched selectively relative to other materials, including other oxides,nitrides, or other exposed materials or dielectrics includingsilicon-containing materials including silicon oxide, or othermaterials. Embodiments of the present technology may etch the transitionmetal materials relative to silicon oxide or any of the other materialsat a rate of at least about 20:1, and may etch the materials relative tosilicon oxide or other materials noted at a selectivity greater than orabout 25:1, greater than or about 30:1, greater than or about 50:1,greater than or about 100:1, greater than or about 150:1, greater thanor about 200:1, greater than or about 250:1, greater than or about300:1, greater than or about 350:1, greater than or about 400:1, greaterthan or about 450:1, greater than or about 500:1, or more. For example,etching performed according to some embodiments of the presenttechnology may etch the noted transition metal materials whilesubstantially or essentially maintaining silicon oxide or othermaterials.

Selectivity may be based in part on precursors used, and the ability todissociate at more controlled temperature ranges. Conventional dryetchants may be incapable of producing etch selectivities of embodimentsof the present technology. Similarly, because wet etchants readilyremove silicon oxide, wet etchants may also be incapable of etchingselectively at rates comparable to embodiments of the presenttechnology. Accordingly, method 400 may provide improved etchcapabilities and selectivities over conventional techniques.

As noted previously, depending on the transition metal material layer,the etchants listed in method 400 may not sufficiently remove thematerials. For example, due to the crystalline or material structure ofthe exposed material, nitrogen trifluoride or the other listedprecursors may not sufficiently dissociate at the temperatures listed,and producing a sufficient envelope of temperature and pressure forselective etching may be frustrated, or may cause damage to otherexposed or underlying structures. Accordingly, an additional method maybe used to selectively remove these transition-metal-containingmaterials.

FIG. 5 shows exemplary operations in a method 500 according toembodiments of the present technology. Method 500 may include some orall of the operations described above with regard to method 400, but mayutilize different halogen-containing precursors, and may etch certaindifferent materials. For example, method 500 may include any previouslydescribed operation, structure, characteristics, or processingcondition, and may be combined or added to any operation discussed abovewith regard to method 400.

As explained above, some transition-metal-containing materials may notreadily or sufficiently etch with nitrogen trifluoride or the othernoted materials. Accordingly, an alternative halogen-containingprecursor may be used based on a transition metal halogen precursor. Forexample, in some embodiments method 500 may include a halogen-containingprecursor including a transition metal and/or that may be characterizedby a particular gas density, as will be explained below. However, asexplained above, these transition metal halogens may not readily etchcertain transition metals. Accordingly, method 500 may include anadditional operation of oxidizing these exposed materials prior toexposure to the transition metal halogen. For example, some of the notedmaterials may include transition metal silicides, which may includeadditional nitrogen and/or oxygen. However, in some of these structures,the nitrogen and/or oxygen may be more closely associated with thesilicon instead of the transition metal, which may be morecharacteristic of the metal itself.

Accordingly, method 500 may oxidize or further oxidize these materialsto increase the oxygen-transition metal bonds. Transition metal halidesmay then readily remove these materials. This may afford improvedremoval of materials being used with increased frequency. For example,many transition metal silicon oxides and transition metal siliconnitrides may be used in barrier layers and around gate structures. Thesedelicate features may be difficult to access with conventionaltechnologies, and improved removal according to the present technologymay allow more regular utilization in semiconductor structures.

Similarly as explained above with method 400, method 500 may optionallyinclude a pre-treatment at operation 505 to clean the substrate and/orremove residues from the transition-metal-containing material surface.The pre-treatment may include any of the materials or operationsdescribed above. At operation 510, an oxygen-containing precursor may beflowed into the substrate processing region housing a substrateincluding the transition-metal-containing material. At operation 515 theoxygen-containing precursor may contact the substrate and exposedtransition-metal-containing material, and may oxidize thetransition-metal-containing material at operation 520.

The oxygen-containing precursor may be any of the oxygen-containingprecursors listed previously, and may be a plasma enhancedoxygen-containing precursor, or may be delivered in a plasma-freeprocess. For example, method 500 may occur at any of the temperatures,pressures, or chamber conditions discussed above for method 400, andthus the substrate or chamber temperature may be sufficient to promoteoxidation. It is to be understood that the oxidation operation may beseparate and distinct from the pre-treatment, which may occur in someembodiments, and the two may include any combination of pre-treatmentsdescribed above, which may further expose or clean atransition-metal-containing material, and oxidation operations, whichmay include specifically oxidizing the transition metal of thetransition-metal-containing material.

Subsequent oxidation of the transition metal material, method 500 mayinclude flowing a halogen-containing precursor into the processingregion at operation 525. As noted above, in method 500, thehalogen-containing precursor may be or include a transition metalhalogen precursor. The halogen-containing precursor may contact thesubstrate and exposed oxidized material at operation 530, and may removethe oxidized transition-metal-containing material at operation 535. Asubsequent post-treatment may be performed at optional operation 540,which may include any post-treatment as described above with method 400.Similar to method 400, 20—although the optional pre-treatment and/orpost-treatment, as well as the oxidation operations of method 500, mayinclude a plasma process, the operations including thehalogen-containing precursor may be performed in a plasma freeenvironment. In some embodiments the halogen-containing precursor may bemaintained plasma free during the etching method.

The halogen-containing precursor in method 500 may include a transitionmetal, as noted. The transition metal may include any transition metalwhich may be capable of bonding with halogens, and which may dissociateunder operating conditions as discussed below. Exemplary transitionmetals may include tungsten, niobium, or any other materials, and mayinclude transition-metal-and-halogen-containing precursors characterizedby a gas density greater than or about 3 g/L, and may be characterizedby a gas density of greater than or about 4 g/L, greater than or about 5g/L, greater than or about 6 g/L, greater than or about 7 g/L, greaterthan or about 8 g/L, greater than or about 9 g/L, greater than or about10 g/L, greater than or about 11 g/L, greater than or about 12 g/L,greater than or about 13 g/L, or higher.

These precursors may be characterized by relatively high thermal andchemical stability because of the nature of bonding between the heavymetal and the halogen. The precursors may also be characterized by atransition metal characterized by relatively low resistivity, which mayfurther facilitate bonding stability at lower temperatures, and faciledissociation at elevated temperatures. Accordingly, the materials may becharacterized by a resistivity of less than or about 50 μΩ·cm, and maybe characterized by a resistivity of less than or about 40μΩ·cm, lessthan or about 30μΩ·cm, less than or about 20 μΩ·cm, less than or about15 μΩ·cm, less than or about 10 μΩ·cm, less than or about 5 μΩ·cm, orless. The precursors may also include any number of carrier gases, whichmay include nitrogen, helium, argon, or other noble, inert, or usefulprecursors, as may also be included with any of the precursors in method400 described above.

Some exemplary precursors that may include the stated characteristicsmay include tungsten hexafluoride, tungsten pentachloride, niobiumtetrachloride, or other transition metal halides. The precursors mayalso be flowed together in a variety of combinations. Etchant precursorsaccording to some embodiments of the present technology may specificallyinclude heavy metal halides, which may be characterized by stability atatmospheric conditions, with relatively facile dissociation at increasedtemperature. For example, exemplary precursors may be characterized byrelatively weak bonding at elevated temperatures, which may allowcontrolled exposure of the oxidized transition metal materials tohalogen etchants.

As a non-limiting example, tungsten hexafluoride may readily donate afluorine atom or two at elevated temperatures, and accept an oxygenatom, such as from the oxidized transition metal material, and bemaintained in a gas phase. Accordingly, tungsten oxide fluorides may bedeveloped as reaction byproducts, which may be gas molecules and may bepumped or removed from the processing chamber, along with transitionmetal byproducts. Accordingly, the process may remove oxidizedtransition metal materials under processing conditions configured toexchange fluorine and oxygen between the etchant and the exposedsurface, and produce volatile transition metal byproducts, and maintaina majority of the tungsten in vapor form. Accordingly, tungsten andother heavy metals similarly encompassed by the present technology mayhave limited or essentially no interaction with the process, whiledelivering halogens to the materials to be etched. Because of thecontrolled delivery, tungsten oxide, tungsten nitride, and other exposedmetal dielectrics may not etch or may minimally interact with otherexposed surfaces, while readily removing the oxidized transition metalmaterials, which may produce enhanced selectivity over conventionaltechniques. For example, the process may similarly etch with any of theselectivities discussed previously for method 400, and may similarlymaintain any of the other noted exposed materials.

The transition metal materials that may be more readily removed withmethod 500 may include materials and structures which may besufficiently oxidized, and may be less prone to facilitate dissociationof fluorine from stronger bonded precursors. For example, nitrogentrifluoride may not as readily dissociate on the surface of sometransition metal materials, further frustrating their removal. Exemplarytransition metal materials that may be etched in method 500 may includetitanium silicon nitride, tantalum silicon nitride, hafnium siliconoxide, hafnium silicon nitride, and certain transition metals, such asmolybdenum. As noted above, certain materials such as hafnium siliconoxide already include oxygen in the structure. However, the oxygen maybe more closely associated with the silicon in these structures, whilethe hafnium may be more closely associated with a metallic bondingstructure. By utilizing an oxidation operation, the hafnium within thehafnium silicon oxide may be oxidized, which may allow removal by theabove-discussed mechanism with a transition metal halide, for example.Similarly, tungsten hexafluoride may not readily etch nitrides, such astitanium nitride and titanium silicon nitride. However, by oxidizing thetitanium and/or the nitrogen, the materials may be readily removed bythe transition metal halogens.

By utilizing methods 400 and/or 500, many transition metal materials maybe removed. Depending on the specific material structure, the ability tobe oxidized, or the dissociation activity of the material to be removedwith certain precursors, the present methods may be used to selectivelyetch the materials. Processing conditions may be utilized as describedto allow gas-phase etching via thermal etch mechanisms, which mayincrease selectivity and reduce material damage relative to conventionaltechnologies.

The previously discussed methods may allow the removal ofhafnium-containing materials relative to a number of other exposedmaterials. By utilizing transition metals as described previously,improved etching of hafnium oxide may be performed, which may bothincrease selectivity over conventional techniques, as well as improveetching access in small pitch features.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theembodiments. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent technology. Accordingly, the above description should not betaken as limiting the scope of the technology. Additionally, methods orprocesses may be described as sequential Or in steps, but it is to beunderstood that the operations may be performed concurrently, or indifferent orders than listed.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Anynarrower range between any stated values or unstated intervening valuesin a stated range and any other stated or intervening value in thatstated range is encompassed. The upper and lower limits of those smallerranges may independently be included or excluded in the range, and eachrange where either, neither, or both limits are included in the smallerranges is also encompassed within the technology, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a precursor” includes aplurality of such precursors, and reference to “the layer” includesreference to one or more layers and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

1. An etching method comprising: flowing a halogen-containing precursorinto a substrate processing region of a semiconductor processingchamber; contacting a substrate housed in the substrate processingregion with the halogen-containing precursor, wherein the substratedefines an exposed region of a transition-metal-containing material; andremoving the transition-metal-containing material, wherein the flowingand the contacting comprise plasma-free operations.
 2. The etchingmethod of claim 1, wherein the halogen-containing precursor comprisesone or more materials selected from the group consisting of nitrogentrifluoride, diatomic fluorine, a precursor comprising carbon andfluorine, and chlorine trifluoride.
 3. The etching method of claim 1,wherein the etching method is performed at a temperature greater than orabout 200° C.
 4. The etching method of claim 1, wherein the etchingmethod is performed at a pressure greater than or about 0.1 Torr.
 5. Theetching method of claim 4, wherein the etching method is performed at apressure less than or about 50 Torr.
 6. The etching method claim 1,further comprising a pre-treatment performed prior to flowing thehalogen-containing precursor, wherein the pre-treatment comprisescontacting the substrate with a plasma comprising one or more of oxygen,hydrogen, or nitrogen.
 7. The etching method of claim 1, furthercomprising a post-treatment performed subsequent the etching method,wherein the post-treatment comprises contacting the substrate with aplasma comprising one or more of oxygen, hydrogen, or nitrogen.
 8. Theetching method of claim 1, wherein the transition-metal-containingmaterial comprises one or more of tungsten, molybdenum, titanium, orchromium.
 9. The etching method of claim 8, wherein thetransition-metal-containing material is selected from the groupconsisting of tungsten, titanium nitride, molybdenum, tungsten silicide,molybdenum silicide, tungsten silicon nitride, tungsten silicon oxide,molybdenum silicon nitride, molybdenum silicon oxide, chromium, chromiumsilicide, tungsten chromium, and molybdenum chromium.
 10. An etchingmethod comprising: flowing an oxygen-containing precursor into asubstrate processing region of a semiconductor processing chamber;contacting a substrate housed in the substrate processing region withthe oxygen-containing precursor, wherein the substrate defines anexposed region of a transition-metal-containing material; oxidizing theexposed region of the transition-metal-containing material to produce anoxidized material; flowing a halogen-containing precursor into thesubstrate processing region of the semiconductor processing chamber,wherein the halogen-containing precursor is characterized by a gasdensity greater than or about 5 g/L; contacting the substrate with thehalogen-containing precursor; and removing the oxidized material. 11.The etching method of claim 10, wherein the halogen-containing precursorcomprises a transition metal.
 12. The etching method of claim 11,wherein the halogen-containing precursor comprises tungsten.
 13. Theetching method of claim 10, wherein the transition-metal-containingmaterial comprises titanium silicon nitride, tantalum silicon nitride,hafnium silicon oxide, hafnium silicon nitride, or molybdenum.
 14. Theetching method of claim 10, wherein the halogen-containing precursor ismaintained plasma free during the etching method.
 15. The etching methodof claim 10, wherein the etching method is performed at a temperaturegreater than or about 200° C.
 16. The etching method of claim 10,wherein the etching method is performed at a pressure greater than orabout 0.1 Torr.
 17. The etching method of claim 16, wherein the etchingmethod is performed at a pressure less than or about 50 Torr.
 18. Theetching method claim 10, further comprising a pre-treatment performedprior to flowing the halogen-containing precursor, wherein thepre-treatment comprises contacting the substrate with a plasmacomprising one or more of oxygen, hydrogen, or nitrogen.
 19. The etchingmethod claim 10, further comprising a post-treatment performedsubsequent the etching method, wherein the post-treatment comprisescontacting the substrate with a plasma comprising one or more of oxygen,hydrogen, or nitrogen.
 20. The etching method of claim 10, wherein theoxygen-containing precursor is plasma enhanced prior to contacting thesubstrate.